The goal of this project is to provide a fundamentally new history of the birth of vaccination. The traditional story of vaccination has been told as a heroic account of Edward Jenner and his discovery of cowpox, and as a result, vaccination remains a triumphant narrative of a medical procedure that worked. Yet Jenner and other early advocates of vaccination encountered many obstacles when they tried to transplant cowpox into new places. My book emphasizes the material culture of vaccination by explaining how cowpox was identified, cultivated, transported, and maintained in various environments around the world -- from the dairies of rural Gloucestershire where cowpox first appeared, to the urban hospitals of London and Paris where the bodies of children and the poor were first used for clinical trials and for supplies of cowpox lymph, to colonial settlements where harsh climates changed the quality of the cowpox lymph. To understand how these many different environments shaped the early practices of vaccination, this book traces the many exchanges of information, illustrations, artifacts, and the cowpox lymph itself among entrepreneurial medical practitioners, clergy, military and colonial bureaucrats, and most significantly women (as mothers and vaccinators), who, up till now, have been excluded from the history of vaccination. Through a careful analysis of correspondence, pamphlets, illustrations, and the technologies for transferring cowpox lymph, this study places the material culture of vaccination at the center of its history. The result will be a definitive r-interpretation of the early history of smallpox vaccination and a new understanding of one of the major revolutions in medicine.